1. Field of the Invention
This invention relates to the field of apparatus for the rearing of insects, entomopathogens and entomophagous agents thereof, and products therefrom.
2. Description of Related Art
The term "entomopathogens" refers to viruses, bacteria, and fungi which infect insects. The term "entomophagous agents" refer to parasites which parasitize insects and predators which prey on insects.
Within the past 20 years, great advances have been made in both the production of insecticidal virus products (IVP) and the utilization of IVPs as safe and effective microbial control agents. Considerable research has led to the registration of four IVPs in the United States as microbial control agents. IVP production can be done in vitro (producing the virus in cell culture) or in vivo (producing the virus in the insect host). For the near term, in vivo production will remain the only practical alternative. The development of semi-synthetic diets facilitated successful mass rearing of hosts for in vivo production (Vanderzant et al). Later improvements in diet and refinement of insect host-virus-environmental factors have led to increased availability of IVPs (Shapiro). Regardless of the insect virus produced and the differences in methodology used by various workers, the basic production scheme involves insect diet/container preparation, insect growth, virus inoculation, virus incubation/larval maturation, and harvest of larvae. In the case of gypsy moth, Lymantria dispar L., production of this insect host and its L. dispar nuclear polyhedrosis virus (LdNPV) has been achieved using a system of carts, trays, and media-filled containers kept in rooms with controlled humidity and temperature. This system begins with the preparation of a high wheat-germ semisynthetic diet which is used as the rearing medium (Bell). Laboratory-reared eggs or their larvae are placed into 180-ml polyethylene cups (15 eggs or 10 larvae per cup) which are filled with 85 ml diet. For egg transfer, disinfected L. dispar eggmasses must be broken up and dehaired to free individual eggs. For neonate transfer, disinfected eggmasses are placed into 100-ml sterile petri dishes for hatching. After capping with paper lids, cups are placed onto 60.times.60 cm polyethylene trays (30 cups/tray), trays are placed horizontally onto 0.6.times.1.2.times.1.8 m mobile carts (18 trays/cart) and carts are wheeled to environmental chambers where insects are reared for 14 days at 26.degree. C., 50% relative humidity (RH), and a photoperiod of 16:8 light:dark (L:D). Fourteen days later, carts are transferred from the environmental chambers, trays are removed from the carts, cups are removed from the trays, lids are removed from the cups, and the diet is surface treated with a viral suspension (1.1.times.10.sup.3 polyhedral inclusion bodies per mm.sup.2. Subsequently, cups are recapped and placed back on carts in the aforementioned manner. Carts are transferred back to environmental chambers where insects and virus are incubated at 29.degree. C., 50% RH and 16:8 L:D photoperiod (Shapiro et al). Fourteen days after infection, when larval mortality is about 75% (e.g. period when virus yield per larva and biological activity of harvested virus are maximal), carts are removed from the environmental chamber and placed in a freezer at -20.degree. C. for 18 hours. Carts are then removed from the freezer, trays are removed from carts, cups are removed from trays, lids are removed from cups, and larvae are removed from the cups and are stored at -20.degree. C. for subsequent extraction and processing of the virus. Freezing prior to harvest is a method for inhibiting bacterial growth within the insect, minimizing tissue histolysis and subsequent loss of virus by leakage into the diet, and synchronizing the production of virus. This rearing scheme allows insects to be reared on the same diet without transfer, with no adverse effects upon larval growth, virus yield, or virus activity. This method of virus propagation, however, has several drawbacks, such as, laborious repeated handling of cups; waste of insect media; inefficient use of space; and the expense of disposable rearing containers.
U.S. Pat. No. 3,727,580 discloses an apparatus for rearing silkworms on horizontal trays which are conveyed through the apparatus during the rearing process. U.S. Pat. No. 2,137,769 discloses a system in which provisions for maintaining desirable conditions of heat and humidity for an enclosure are located exterior to the enclosure. U.S. Pat. No. 2,539,633 discloses a device for breeding insects in which a vertical breeding tray is suspended by hooks and eyes from the top of the device. The breeding tray is constructed of wood or metal, has wire screening sides, and contains grain. U.S. Pat. No. 3,750,625 discloses a plastic insect breeding tray with multiple cup-like compartments and with egg receiving recesses connected to the cups by crawl passages. U.S. Pat. No. 4,572,427 discloses a controlled atmosphere enclosure with a recirculation path which includes a blower, a filter, a carbon dioxide sensor, and a humidifier. The system is controlled by a microprocessor.
The present invention overcomes the spatial/temporal drawbacks of conventional methods by providing a self-contained unit with a vertical array of media leaves and a computer controlled environment. Use of the invention involves performance of fewer functions on far fewer units than are required with the traditional rack/tray/cup system. The problems associated with contamination of cups with molds are avoided with this invention. This invention reduces the costs of producing insects, entomopathogens thereof, insect parasites, and other insect products.